Photoluminescence Switching and Non-Volatile Memory in Hybrid Metal-Halide Phase-Change Materials

Phase-change materials (PCMs) have spurred intensive
studies for
information storage owing to huge and drastic changes in physical
properties (i.e., optical and resistivity) during the phase transitions
between crystalline-amorphous and crystalline-melting-glassy states.
However, limited switching properties and materials greatly hinder
their development and applications. Herein, we report a pair of hybrid
metal halides (R/S-2-HMM)3SbCl6 (2-HMM = 2-(hydroxymethyl)­morpholine cation) as
model compounds of a new class of photoluminescent PCMs. They undergo
a stable melt process and become amorphous glass by melt-quenching.
The crystalline phase exhibits near-unity yellow photoluminescence
with a 95% quantum yield due to the radiative recombination of self-trapped
excitons in the excited state of [SbCl6]3– octahedra. The glass phase exhibits an orange emission with a very
low quantum yield and good transparency in the 400–800 nm range.
Drastic photoluminescence switching via the crystal-glass transition
is exploited for rewritable phase-change memory, as exemplified by
a 4 × 4 array model device. The robust crystal–liquid–glass
phase changes in hybrid metal halides and drastic photoluminescence
switching open a new avenue to PCMs for further applications in remote
information storage, sensing, and display.